Magnetic actuator device with coupled rotors



Jan. 17, 1967 F. R. ADAMS 3,299,331

MAGNETIC ACTUATOR DEVICE WITH COUPLED ROTORS Filed May 2, 196e 1 'j /NvE/vroR {Q7/WZ 42u/w 4+ 42 By 5 33 A Tran/vers United States atent flice 3,299,381 MAGNETIC ACTUATQR DEVICE WITH COUPLED ROTRS Frank R. Adams, 2625 Ruger Ave., Janesville, Wis. 52505 Filed May 2, 1966, Ser. No. 546,978 7 Claims. (Cl. 335-232) The herein described invention is a continuation-impart of my pending application, Serial No. 452,738 filed May 3, 1965 for the invention entitled Proportional Magnetic Actuator Device.

This invention relates to improvements in magnetic type actuators which slave to pulsed radio signals and more particularly, relates to a magnetic actuator or selfneutralizing servo having a pair of coupled magnetic rotors to provide significantly increased torque output from a single magnetic rotor configuration without increase in volatge or amperage applied to the electromagnet.

The self-neutralizing servo with which this invention is concerned is of the general type described and illustrated in my Patent No. 2,771,572.

The magnetic actuator of said Patent 2,771,572 andof said :application Serial No. 452,738 enables the use of a proportional system for operating a control means such as the steering mechanism of a radio-controlled .model vehicle to which the output shaft of the actuator is connected. rl`he advantages of such a proportional control system are recognized and the patented :actuator device as well as t-he device of said copending application have been commercially successful in their use for operating a steering mechanism of a radio-controlled model vehicle. FIhis actuator employed -a permanent magnet rotor which was made to oscillate in response to selective direct current energization of the coil windings around a ferrous core to which ferrous pole pieces are connected.

It is the primary object of this invention to provide a magnetic actuator of the character described in which a simple center tapped electromagnet is utilized to oscillate a pair of permanent magnet rotors which are coupled together by la non-ferrous coupling member for transmitting the torque of one rotor to the other whereby an increase of approximately two to three times the torque output is realized over that of the single rotor unit with no increase in voltage or `amperage applied to the electromagnet.

Another object of the invention is to provide a magnetic actuator of the character described in which the indexing means of said copending application Serial No. 452,738 is employed for each pair of pole pieces used in each of t-he two rotor assemblies. The purpose of the indexing means is to provide more angular travel of the rotor in each direction of rotation from the neutral position and to provide higher torque output up to the point of alignment of the magnetic pole of the rotor with the force field leak at the restricted cross section area indexing point than can be achieved without the indexing means.

Another object of the invention is to provide an actuator device of the character described which enables such increase in torque output to be realized without substantial increase in the size and cost of the actuator device as compared to the actuator device of said Patent 2,771,572 or said application Serial No. 452,738.

The foregoing and other objects of the invention will become apparent from the ensuing disclosure in which a preferred embodiment has -been described in detail and illustrated in the accompanying drawings. Minor variations in structural features of said magnetic actuator embodiment may occur to the skilled artisan without depart- 3,299,381 Patented Jan. 17, 1967 ing from the scope or sacrificing any of the advantages thereof.

In the drawings:

FIG. 1 is a diagrammatical -view showing the magnetic actuator device embodying the invention installed in a representative operational system for which the invention is particularly suitable.

FIG. 2 is a perspective view of said magnetic actuator on an enlarged scale.

FIG. 3 is a median sectional View taken longitudinally through said magnetic actuator.

FIG. 4 is a sectional view taken through said actuator along the lines 4-4 of FIG. 3 and in the general direction indicated.

FIG. 5 is a plan view of the actuator lhaving a modified form of coupling means for connecting the magnetic rotors.

Referring now to the drawings, in FIG. l there is shown diagrammatically the magnetic type actuator embodying the invention installed in a radio-controlled model automobile for proportional control of the steering mechanism of said automobile. The illustration shows said actuator in an operational environment for which it is very suitable, that is, for operating the linkage to the front wheels of an automobile which requires considerable torque. As seen in FIG. l, the linkage to the front wheels 10 of the automobile 12 includes a tie rod 14 which is connected `by the links 16 to the front wheels. Extending rearwardly from thev tie rod is a linkage 18 which terminates in a loop 19 operably connected to the magnetic actuator embodying the invention which has been identified generally by the reference character 2t).

The linkage 18 is rotated reciprocably as represented by the arrow 21 by the actuator 20 and said rotary movement is then translated into a linear movement which likewise is a reciprocating one as represented by the arrow 22 along which the tie rod is moved to `turn the wheels in the direction indicated by the arrows 23. Since the specic structure of the steering mechanism for the wheels and the linkage for operating said steering mechanism through the actuator 20 is not a part of the herein invention and further since these mechanical elements can vary in structure within wide limits, it is not deemed necessary to describe or illustrate the same in any greater detail. The herein invention is concerned with the magnetic actuator 20.

Referring to FIG. 2, the magnetic actuator 20 includes an electromagnet shown with a ferrous core 61 which is provided with a hole for a bolt 31 as best seen in FIG. 3. Also shown is the coil winding 32 which can be either a single coil of wire that is center tapped at mid-resistance with proper terminal connections, or a pair of coils,

wound in series, with the series connection as the center tap. The core 61 supports a pair of plastic. end flanges or discs 33, one of said flanges 33 mounting three terminals orcontacts 34, 35 and 36 for the terminal leads and center tap of the coil to which electrical leads 37, 38 and 39, respectively, are connected. As understood in the art, the coil 32 is connected to be selectively energized from a battery or direct current supply by means of the radio receiver which controls operation of a suitable switching arrangement. Where the switching arrangement connects the battery supply .across leads 37 and 38, the core 61 is magnetized to achieve one condition of polarity for the pole pieces. To reverse the condition of polarity of the pole pieces, the battery supply is connected across the leads 38 and 39, maintaining the same electrical polarity at center tap 38. Thus the lead 38 is a center tap .and leads 37 and 39 are terminal leads for selectively energizing the coil 32 from a battery supply, not

shown, in response to signal received from a pulsed transmitter by a receiver in the model vehicle.

As thus far described, the actuator 20 is substantially identical in construction to the actuator of said cepending application. In fact the size of the corre 61 and theA coil winding 32 are identical. Also, the contacts 34, 35 and 36 are identical in each of the said actuators. Using this arrangement in the herein invention I can provide a pair of rotors which are controlled by energization of the single core and coil which I have heretofore used in my actuator of application Serial No. 452,738, as will now be explained.

Referring to FIGS. 3 and 4 herein, I have provided two pairs of polar arms extending in opposite directions from each end of the core 61. The first pair of polar arms 40 and 42 are provided at their extremities remote from the core with pole pieces 43 and 44 respectively. Each arm is an integral part or extension of the pole piece, Each of said spole pieces is a fiat strip of ferrous metal of uniform width and thickness substantially semicircular in youtline at a rig-ht angle to the polar arrn of which it is la part. Thus, the pole pieces 43 and 44 are aligned facing each other in a common plane spaced from the axis of the core and with their respective extremities 45, 45 spaced apart to provide air gaps 46 and 46', respectively.

The pole pieces 43 and 44 are joined to a non-magnetic disc 47 in the manner disclosed in said copending aplplication Serial No. 452,738. The disc 47 has an integral tubular bearing 48 for a rotatable shaft 49. The rotatable shaft 49 has a right angle extension 50. The shaft 49 fixedly supports a permanent magnet 51 lmagnetized along its diameter, which is rotatable with the shaft, the shaft 49 extending axially through the center of the disc 47 and being bent to facilitate secural, as by soldering and cementing to the surface `of the magnet 51.

The pole pieces are secured to the disc 47 by the hollow non-ferrous rivets 55, 56, 58 and 60. Rivets 55 and 60 are spaced apart 180, as are rivets 58 and S6, on the pair of pole pieces, and each rivet hole provides a region of reduced cross-'sectional area in each arm of each pole piece as a fiux restriction. Rivets S and 56 hold the disc 47 to the pole piece 43 and rivets 58 and 60 hold the pole piece 44 to the disc 47, the flux restrictions at the rivet locations serving as magnetic indexing means as described and claimed in said copending application Serial No. 452,738.

Further, the actuator has a second pair of polar arms 40a and 42a which are connected to the core 61. The polar arms 40a and 42a have as integral parts pole pieces 43a and 44a respectively. In fact, the invention contemplates the provision of a second rotor assembly on the opposite side of the core which is identical to the rotor assembly heretofore described, Consequently, the same ordinal numbers have been assigned to the corresponding elements of said rotor assembly with the additional use of the sub-script a to distinguish one from the other. However, the nexus of the invention resides in thelprovision of such a pair of similar rotor assemblies with the individual 'assemblies on opposite sides of the common core to which they are connected. Thus the right angle extensions S0 and 50a of the shafts 49 and 49a respectively are coupled together adjacent their free extremities at 52 and 52a by a coupling member 54 of non-ferrous material, -or of discontinuous ferrous material forming two coupling stubs connected by a non-ferrous loose fitting insulating sleeve 54. The use of sleeve 54 to connect the two coupling stubs allows some rnisalignment of bearings 48 and 48a in assembly without the resulting torsional output losses which a firm coupling of the two rotors could cause. The coupling member S4 is operably connected to the loop 19 by passing therethrough as shown in FIG. 2.

The magnets of the two rotor assemblies are arranged parallel in their polarities such that the shafts 49 and 49a are rotated in the same angular direction concurrently. The torque output end of the rotors is thereby coupled one to the other and an increased total routput is realized from the single electromagnet without any increase in voltage or `amperage thereto.

A commercial embodiment of this invention has been successfully marketed with entirely unexpected and unusual results. The torque output from the actuator 20 was approximately two to three times the output realized from the -actuator of said application Serial No. 452,738 notwithstanding the use of identical core 61 and coil 32 as in actuator 20. The output of a device embodying the actuator of application Serial No. 452,738 was measured at nine to nine and one half inc-h grams of torque. The output of a device of the actuator 20 herein using the same size electromagnet and rotor assembly was measured at twenty-four to twenty-seven inch grams. The electromagnet of the device 20 herein as well as said prior actuator consisted of 1050 turns of No. 34 copper wire insulated in each of the two coils, Voltage applied in both cases was 4.8 v. from fully charged nickel cadmium cells of 1.2 ampere hours capacity with la resultant current drain of milliamperes. The reason for obtaining this unexpected and unusual result is not entirely understood but may be hypothesized Vas follows: In the single lrotor configuration actuator of application Serial No. 452,738, the lines of magnetic force created in the core of the electromagnet by energization with direct current of one coil or the other attempt to close the circuit magnetically by following the path of least reluctance, i.e., the polar arms Iand pole pieces. The pole pieces will accept lines of magnetic force only to a point of saturation, usually considered to be approximately 110,000 lines of force iper square inch of cross-sectional area in cold rolled steel. At saturation of the pole pieces, the reluctance of the magnetic circuit is raised to a level where no more lines of magnetic force may enter the pole pieces. Leakage of lines of force will then occur through air from one end of the coil core to the other since this now has become the new path of least reluctance,

In the two rotor configurations herein, with rotors coupled together, the addition of a second pair of polar arms Iand pole pieces furnishes `a new path of lower reluctance than the air path existent in the single rotor configuration. The addition of the two polar arms and pole pieces creates a total flux path of approximately one-half the reluctance of the path -of the single rotor configuration, plus the advantage of gathering in a portion of the stray or lost lines of force wasted in the single rotor configuration. It is believed that the more than double torque output at the same voltage and amperage is the result of more efficient utilization of available lines of magnetic force created by the energized electromagnet. It is also very probable that the effect of having two permanent magnets in the flux path may aid in shaping and lconfining the stray lines of force that occur above the saturation level of the polar arms.

The invention contemplates applying the torque output from the actuator 20 other than from the coupling member connecting the rotor assemblies. Looking at FIG. 5, the actuator 20 has been modified to couple the magnets 51 and 51a by means of a coupling member 62 which is formed by extending the inner end -of each shaft 49 and 49a into an L-shaped extension 64 and 64a. The extremities of these extensions are then coupled by a sleeve 66 of insulating material thus coupling the rotor assemblies from the inner ends of the shafts 49 and 49a. Thereafter, the output end of one shaft 49 or 49a is connected to the coupling loop 19, for instance. For instance, the extension 50 could be dispensed with and the extension 5017 formed for connection to operate the control device by means of a torque rod or push rod.

It is believed that the invention has been described in y sufficient detail to enable the skilled artisan to understand and practice the same. What it is desired to secure by Letters Patent of the United States is specically pointed out in the claims hereto appended as follows.

What is claimed is:

1. A light-Weight magnetic actuator for controlling a model vehicle comprising,

(la) an electromagnet having a core and a winding on the core,

(b) a pair of magnetizable assemblies connected to opposite ends of the core and selectively energize-d thereby,

(c) said assemblies arranged on opposite sides of and spaced from the core,

(d) each assembly including magnetizable pole pieces disposed in a common plane t-o complete la separate magnetic circuit, and -a permanent magnet member mounted in a plane parallel to said common plane,

(e) each magnet member having a rock shaft joined for movement therewith for providing a mechanical output, and

(f) non-magnetic coupling means connecting said magnets to provide a common mechanical output from both of said rock shafts.

2. A magnetic actuator as described in claim 1 in which said rock shafts are coupled together by said coupling means.

3. A magnetic actuator as described in claim 1 in which 6 each rock shaft is secured to a surface of the magnet associated therewith, and each rock shaft has an output end connected with the output end of the other rock shaft by said coupling means.

4. A magnetic actuator as described in claim 3 in which the assemblies are substantially identical.

5. A magnetic actuator as described in claim 1 in which each rock shaft is secured to a surface of the magnet associated therewith, and each rock shaft has an output end connected with the output end of the other rock shaft by said coupling means, said output ends of the rock shlaft being an extension of the portion of the shaft secured to the magnet surface.

6. A magnetic actuator as described in claim 2 in which said rock shafts each have an output end remote from the magnet associated therewith and said outputs ends yare coupled together by means of a non-magnetic coupling sleeve.

7. A magnetic actuator as described in claim 1 in which indexing means are provided on each pair of pole pieces.

No references cited.

BERNARD A. GILHEANY, Primary Examiner. G. HARRIS, Assistant Examiner. 

1. A LIGHT-WEIGHT MAGNETIC ACTUATOR FOR CONTROLLING A MODEL VEHICLE COMPRISING, (A) AN ELECTROMAGNET HAVING A CORE AND A WINDING ON THE CORE, (B) A PAIR OF MAGNETIZABLE ASSEMBLIES CONNECTED TO OPPOSITE ENDS OF THE CORE AND SELECTIVELY ENERGIZED THEREBY, (C) SAID ASSEMBLIES ARRANGED ON OPPOSITE SIDES OF AND SPACED FROM THE CORE, (D) EACH ASSEMBLY INCLUDING MAGNETIZABLE POLE PIECES DISPOSED IN A COMMON PLANE TO COMPLETE A SEPARATE MAGNETIC CIRCUIT, AND A PERMANENT MAGNET MEMBER MOUNTED IN A PLANE PARALLEL TO SAID COMMON PLANE, (E) EACH MAGNET MEMBER HAVING A ROCK SHAFT JOINED FOR MOVEMENT THEREWITH FOR PROVIDING A MECHANICAL OUTPUT, AND (F) NON-MAGNETIC COUPLING MEANS CONNECTING SAID MAGNETS TO PROVIDE A COMMON MECHANICAL OUTPUT FROM BOTH OF SAID ROCK SHAFTS. 